As a heat-insulating container made paper mainly used for instant dried Chinese noodles, there has widely been used a container in which a paper cup body surrounded over its outer periphery with a heat-insulating corrugated member having narrow projections and recesses arranged alternately.
The heat-insulating member of the heat-insulating container has the above-mentioned irregularity so that characters, designs or the like printed on its surface appear extremely unclearly, thus making it impossible to give the high-grade appearance of design to the container.
In Japanese Patent Provisional Publication No. H8-113274, there is proposed a heat-insulating container in which the width of the recesses of the heat-insulating member is made smaller than that of the projections so that the total area of clearly visible portions on the outer periphery of the container is increased. However, the recesses appearing on the outer periphery of the container do not provide complete solution of the above-mentioned problems.
In Japanese Patent Provisional Publication No. S49-87479, Japanese Patent Provisional Publication No. H4-45216 and Japanese Patent Provisional Publication No. H8-104373, there is proposed a heat-insulating container, in which a heat-insulating member subjected to a corrugating process or an embossing process is surrounded with a liner or a shin sheet of paper so that no irregularity is formed on the outer surface of the container. Such a container can solve the problems of the appearance on its outer periphery. However, the bottom of the heat-insulating container may have irregularity in the joined portions of the heat-insulating member and the liner. When observation from the bottom side of the container is made, the edge of the corrugated or embossed heat-insulating member appears through a gap formed in the bottom of the container. Dirt or liquid may enter the gap of the bottom of the container, thus causing insanitary problems. The additional liner provides an increased production cost.
In Japanese Utility Model Provisional Publication No. 4-45212, there is proposed a heat-insulating container in which a heat-insulating property is ensured without using any heat-insulating member having irregularity. The heat-insulating container has for example a construction as shown in FIG. 11. More specifically, the heat-insulating container 100 is provided with a paper cup body 101 having a bottom plate 102 and a side shell-wall 103 and with a tubular member 105 arranged on the outer periphery of the side shell-wall 103. The paper cup body 101 and the tubular member 105 come on their opposite edges into contact with each other to be joined with each other into an integral body. The side shell-wall 103 is provided on its upper edge with an inward curled portion 104. The tubular member 105 is provided on its lower edge with an inward curled portion 106. A heat-insulating space corresponding to the thickness of the curled portion 106 is formed between the side shell-wall 103 and the tubular member 105.
Such a heat-insulating container 100 does not use any specific heat-insulating member having irregularity and has therefore no disadvantage caused by the heat-insulating member. When the container is actually held at the central portion of the side shell-wall thereof with a hand, the tubular member may however easily be deformed inward to decrease the capacity of the heat-insulating space, thus deteriorating the heat-insulating property.